Discharging device for ball mills



Fi1ed Feb. 7, 1941 2 sheets-sheet 1 D. A` YASENEV ETAL DISCHARGING DEVICE FOR BALL MILLS Dems, 1943.

Dec. 28, 1943. D. A. YAsENEv ETAL 2,337,704 DISCHARGING DEVICE FOR BALL MILLS Filed Feb. 7, 1941 2 Sheets-Sheet 2 Patented ec. 28, 1943 Ul'l'ED Sri" EENT OFFRE DSCHRGING DEVCE FR BALL MILLS Dmitry Andrcevitch Yasenev, Sverdlovsk, and Michael Alexandrovtch Perevalov, Molotovo, Union of Soviet Socialist Republics 3 Claims.

Discharging devices are used with ball mills in order to increase their output and to decrease simultaneously the specific expenditure of power. The first primitive discharging devices installed in the Marcy mills in 1915 proved to increase the output of the mills by Sil-80% and to reduce the power expense by about 30%. The following achievements gave as result the existing American mills or Allis-Chalmers and the ABCO mills of the American Ball Mill Company.

The first of the cited mills shows an additional grate allowing for the regulating of the pulp level in the mill and cooperating to the achievement of the necessary effect of ore reducing. High circulating loads however are not granted with the cited mill.

The discharging device of the ABCD mills, issued in i936 grants high circulating loads improving at the same time the working conditions of the previous types of ball mills. However this type possesses its own structural defects and moreover lacks the device intended to regulate the level of the pulp, as used in the Allis- Chalmers mill.

Thus contemporary types f discharging devices in ball mills show defects, the most important of which are:

(1) A considerable quantity of complicated details, expensive in their make and necessitating a painstaking and laborious assemblage.

(2) Diiliculties in substitution of worn parts, necessitating an almost complete dismounting of the discharging end of the mill.

(3) Blocking of the discharging device by the grinding bodies.

The proposed device is intended to eliminate the above mentioned defects and at the same time grants high circulating loads as Well as provides means for regulating the level of the ground material.

In the accompanying drawings Fig. 1 shows a longitudinal section of the discharging end of the mill.

Fig. 2 shows an interior view upon the mill discharging device with the armoured plates partly removed.

Fig. 3 shows a cross-section of the screen.

Fig. 4 is a view from outside upon the end face of the discharging wall of the drum, showing the assemblage of the screen.

The discharging device consists of a body l, subdivided by means of radial partitions in an even series of chambers (in the given case there are six chambers. Certain of these partitions are solid or continuous as at 2 while alternate partitions are each provided with an opening 3, wherein the screen is fastened. The chambers are covered adjacent the working space by armoured plates, some of which are continuous as at 5 while alternate plates are provided with a series of openings of oval shape 6. The central outlet of the body l holds a distributor l, the channels of which connect the chambers alternatively with the discharging funnel or either with the working space of the mill. The method by which the separate members of the screen d are fastened to the frame 3 in Fig. 3 provides for their displacement in longitudinal and transverse directions. The screen frame is assembled completely with the screen by means of the plate 9, which is fastened by screws and covers an opening in the end-face of the mill; the frame is easily removed through this opening, not involving a dismounting of the mill.

The operation of the discharging device is as follows: the crushed material penetrates from the Working space of the mill through the openings 6 in the armoured plates into the chambers d and from there is carried along with the rotation of the drum of the mill, whereby the particles which are of sufficiently fine grinding pass through the screen and enter the chambers b. Therefrom the material enters the discharging funnel by way of the distributor channel c and is discharged from the mill.

The particles which are not gro-und to the desired size slide over the surface of the screen and are returned by way of the channels d of the distributor to the working space of the mill.

The advantages of the present discharging device when compared to existing types of such devices are:

(1) The screens are completely protected from injuries owing to the grinding bodies and the large pieces of material, thus greatly increasing their resistance (wear and unriveting).

(2) Blocking of the screens is eliminated owing to the particular construction granting the mobility of the gratings in longitudinal and transverse directions.

(3) A removal and change of the screen is excessively easy owing to the fastening o1" the screen on the outer side of the end-face of the mill.

(4) The live section of both armoured plates and screens is fully opened to the flow of the material.

(5) A regulation of the level of the material in the mill is possible by means 0f closing of a part of the openings in the armoured plates which is performed through hatches l in'the end-face wall.

(6) The openings in the armoured plates cannot be blocked owing to their oval conic form.

(7) The quantity of details that are to be made of alloyed steel is limited and practically is brought down to the armoured plate only, which possess a plain form and are therefore easy to manufacture.

(8) The fastening of the discharging device to the body of the mill is excessively easy.

The enlarged live section of the screenings, the elimination of their blocking and the lowered level of the material together with the return of the oversized particles to the working space results in high circular loads of the mill of the proposed invention.

Having thus described the invention and the manner in which it is to be performed, we herewith state, that what we claim is:

l. A discharging device for ball mills comprising a plate-like body for attachment to the rotating discharge end of the drum of a mill and having a central discharging outlet and including a series of radially arranged partitions on the inner face of the body providing a series of charnbers, certain of the partitions being solid while alternate partitions are provided with openings situated on the discharging side of the chamber, screens fitted in said openings to provide passageways to the adjacent closed chambers, cover plates arranged on the inner edges of the partitions to close the chambers from the working space of the mill, alternate plates having openings thereby to allow material to pass into those chambers tted with the discharging screens, a distributor tted centrally of the plate-like body in advance of the central discharging outlet and having channels respectively placing the closed chambers in communication with the central discharging outlet for discharging ne material and placing the chambers having the discharging screens in communication with the working space of the mill to return insufciently ground material thereto.

2. A discharging device as claimed in claim l, in which the screens are composed of a plurality of separate members and means for fastening the members together in such manner as to allo-W of limited longitudinal and transverse movement relative to each other.

3. A discharging device as claimed in claim l, in which a member is provided serving as the end face of the mill and carries the plate like body and outlet and is further provided with openings located adjacent the apertured partitions, the plate like body being also provided with openings registering with the openings in the said member in order that the screens may be inserted exteriorly of the mill and means for detachably fastening the screens as units to the member in such manner that they will occupy the proper position in the openings in the apertured partitions.

DMITRY ANDREEVITCH YASENEV. MICHAEL ALEXANDROVITCH PEREVALOV. 

